The present invention generally relates to power tools and, more particularly, to power table saws.
Power table saws typically have guard systems that either attach to the undercarriage of the table saw, to the rear of the table saw or to some structure above the table saw. In each of these configurations there are typically three components, namely, a splitter or riving knife, a kickback prevention device, (often called kickback dawgs) and a blade guard that covers the blade. A riving knife is a safety device that reduces the likelihood of a kick-back event where a work piece is somehow caught or bound up during a cutting operation and the inertia of the blade throws the work piece back toward the user.
A blade guard mechanism that is configured to be releasably attached to the riving knife can comprise an upper guard barrier oriented generally horizontally, i.e., preferably parallel to the table. The mechanism has a mounting portion that includes a quick release mechanism and a pair of side barriers that are pivotally attached to the mounting portion.
Such a blade guard construction is disclosed in application Ser. No. 11/890,891 filed Aug. 8, 2007 and entitled MODULAR TABLE SAW GUARDING SYSTEM UPPER GUARD BARRIER, which is specifically incorporated by reference herein.
There are table saw guard standards that have been established by Underwriters Laboratory Standard 987, section 40, which is scheduled to go into effect in the year 2010. The standard requires that a table saw riving knife maintain a standard spacing away from the table saw blade and support the guard through its range of motion. Present table saw guard systems which utilize a riving knife and which meet the 2010 standards have a mechanism which moves the entire motor and blade vertically to accomplish the various blade height positions. These designs are effective, but are relatively expensive compared to a pivoting mechanism that move the blade and motor through an arc to accomplish various blade height positions.
Such pivoting designs are typically lower in cost. In order to meet the regulatory standards, it is necessary to move the riving knife vertically while the blade and motor move through an arc defined by the motor pivoting mount.